Supporting Deano’s comments – now what do you think all those petrol voucher dockets are for? To determine when you have money in your pocket, they know roughly what areas where you live (as people generally buy groceries close to home) and that helps then determine when to set the prices lower for each store.

Per store pricing is standard practice for nearly all major retailers and not just groceries. They spend considerable sums of money understanding the demographics and preferences of shoppers in the area and set prices to what they believe will maximise their profit. Prices can also be influenced by the local competition.

Aldi are the only chain that has consistent prices across all stores, which is part of their keep it simple operating strategy.